LM6317 120 MHz Fast Settling Low Power Voltage Feedback Amplifier
November 1995
LM6317
120 MHz Fast Settling Low Power
Voltage Feedback Amplifier
General Description Features (Typical unless otherwise noted)
The LM6317 is a high speed unity-gain stable voltage feed- Y Easy to use voltage feedback topology
back amplifier that consumes only 40 mW of quiescent pow- Y Unity-gain stability
er Operating at g 5V power supply the LM6317 provides Y Wide unity-gain bandwidth 120 MHz
excellent AC performance such as 120 MHz of unity-gain Y Fast slew rate 1100V ms
bandwidth 1500V ms of slew rate and 80 dB of SFDR Y Fast settling time
The LM6317 has the slew characteristic of a current feed- 0 1% 12 ns
back amplifier yet it can be used in all traditional amplifier 0 01% 18 ns
configurations The high output current and good stability Y Low SFDR 1 MHz Driving 100X 80 dB
with capacitive load of LM6317 makes it ideal for driving Y High output current 60 mA
cables With its unity-gain stability fast settling time and low Y High CMRR and PSRR 80 dB 74 dB
output impedance the LM6317 can be used to buffer A D
converters The LM6317 also has very low input voltage and
Y Low supply current 4 mA
current noise high CMRR and PSRR desirable in precision
Y Specified for g 5V operation
applications such as ATE systems
Applications
Y Active filters
Y A D Converter buffers
Y Video cable drivers
Y Communication systems
Y Portable systems
Y Ultrasound equipment
Y ATE systems
Typical Performance Connection Diagram
Settling Time vs Gain 8-Pin DIP SO
TL H 12542 – 2
Top View
TL H 12542 – 14
Ordering Information
Temperature Range
Transport NSC
Package Industrial Media Drawing
b 40 C to a 85 C
8-Pin DIP LM6317IN Rails N08E
8-Pin Small Outline LM6317IM Rails
M08A
LM6317IMX 2 5k Tape and Reel
TinyPakTM is a trademark of National Semiconductor Corp
C1996 National Semiconductor Corporation TL H 12542 RRD-B30M76 Printed in U S A http www national com
Absolute Maximum Ratings (Note 1) Operating Ratings (Note 1)
If Military Aerospace specified devices are required Supply Voltage g 2 3V s VS s g 6V
please contact the National Semiconductor Sales Junction Temperature Range b 40 C s TJ s a 85 C
Office Distributors for availability and specifications
Thermal Resistance (iJA)
ESD Tolerance (Note 2) N Package 8-Pin Molded DIP 110 C W
Human Body Model 1 5 kV M Package 8-Pin Surface Mount 170 C W
Machine Model 200V
Supply Voltage (V a – Vb) 12V
Differentfial Input Voltage 10V
Output Current (Note 3) g 60 mA
Storage Temperature Range b 65 C to a 150 C
Maximum Junction Temperature (Note 4) 150 C
g 5V DC Electrical Characteristics Unless otherwise specified all limits guaranteed for TJ e 25 C
V a e a 5V Vb e b5V VCM e 0V and RL e 100X Boldface limits apply at the temperature extremes
Typ Limit
Symbol Parameter Conditions Units
(Note 5) (Note 6)
VOS Input Offset Voltage 5 mV
03
7 max
TC VOS Input Offset Voltage
8 mV C
Average Drift
IB Input Bias Current 12 mA
3
22 max
IOS Input Offset Current 2 mA
02
4 max
RIN Input Resistance Differential 2
MX
Common 1
CIN Input Capacitance Differential 1
pF
Common 1
RO Open Loop Output
0 02 X
Resistance
CMRR Common Mode VCM e g 1 5V 62 dB
80
Rejection Ratio 57 min
PSRR Power Supply VS e g 5V to g 4 5V 60 dB
74
Rejection Ratio 52 min
AV Large Signal VOUT e g 1V 55
70
Voltage Gain RL e 1 kX 50 dB
VOUT e g 1V 53 min
67
RL e 100X 48
VCM Input Common-Mode CMRR e 60 dB 26 V
32
Voltage Range 23 min
b2 6 V
b3 2
b2 3 max
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g 5V DC Electrical Characteristics (Continued) Unless otherwise specified all limits guaranteed for TJ e
25 C V a e a 5V Vb e b5V VCM e 0V and RL e 100X Boldface limits apply at the temperature extremes
Typ Limit
Symbol Parameter Conditions Units
(Note 5) (Note 6)
VO Output Swing RL e 1 kX 3 V
35
26 min
b3 V
b3 5
b2 6 max
RL e 100X 25 V
3
23 min
b2 5 V
b3
b2 3 max
IS Supply Current 6 mA
4
7 max
g 5V AC Electrical Characteristics
Unless otherwise specified TJ e 25 C V a e a 5V Vb e 5V AV e 1 and RL e 100X
Typ
Symbol Parameter Conditions Units
(Note 5)
SR Slew Rate 5V Step 1100
5V Step AV e b1 V ms
750
RL e 500X
Unity-Gain Bandwidth AV e b1 RL e 500X 120 MHz
b 3 dB Frequency AV e a 2 80 MHz
im Phase Margin AV e b1 RL e 500X 60
ts Settling Time 0 1% 2V Step 12
ns
0 01% 2V Step 18
en Input-Referred Voltage Noise f e 100 kHz 42 nV
0Hz
in Input-Referred Current Noise f e 100 kHz 2 pA
0Hz
Note 1 Absolute Maximum Ratings indicate limits beyond which damage to the device may occur Operating Ratings indicate conditions for which the device is
intended to be functional but specific performance is not guaranteed For guaranteed specifications and the test conditions see the Electrical Characteristics
Note 2 Human body model 1 5 kX in series with 100 pF Machine model 200X in series with 100 pF
Note 3 Applies to both single-supply and split-supply operation Sourcing and sinking more than 60 mA at the output may adversely affect reliability
Note 4 The maximum power dissipation is a function of TJ(max) iJA and TA The maximum allowable power dissipation at any ambient temperature is PD e
(TJ(max) –TA) iJA All numbers apply for packages soldered directly into a PC board
Note 5 Typical values represent the most likely parametric norm
Note 6 All limits are guaranteed by testing or statistical analysis
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Typical Performance Characteristics Unless otherwise noted TA e 25 C VS e g 5V
Supply Current IB and IOS vs PSRR CMRR and
vs Supply Voltage Common-Mode Voltage Closed Loop Ro
TL H 12542–3 TL H 12542 – 4 TL H 12542 – 5
Open Loop Bandwidth Bandwidth
Frequency Response vs Supply Voltage vs Capacitive Load
TL H 12542 – 7 TL H 12542 – 8
Non-Inverting Inverting Frequency
Frequency Response Response Equivalent Input Noise
TL H 12542–9 TL H 12542 – 10
TL H 12542 – 11
2nd and 3rd Settling Time vs Maximum Power Dissipation
Harmonic Distortion Capactive Load vs Ambient Temperature
TL H 12542–12 TL H 12542 – 13 TL H 12542 – 24
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Typical Performance Characteristics Unless otherwise noted TA e 25 C VS e g 5V (Continued)
Large Signal Pulse Response Small Signal Pulse Response
(AV e a 1) (AV e a 1)
TL H 12542 – 1 TL H 12542 – 15
Large Signal Pulse Response Small Signal Pulse Response
(AV e b1) (AV e b1)
TL H 12542 – 16 TL H 12542 – 17
Large Signal Pulse Response Small Signal Pulse Response
(AV e a 2) (AV e a 2)
TL H 12542 – 18 TL H 12542 – 19
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Application Notes
COMPONENTS SELECTION AND FEEDBACK RESISTOR
Using the LM6317
It is important in high speed applications to keep all compo-
LIMITS AND PRECAUTIONS nent leads short because wires are inductive at high fre-
The absolute maximum supply voltage which may be ap- quency For discrete components choose carbon composi-
plied to the LM6317 is 12V Designers should not design for tion-type resistors and mica-type capacitors Surface mount
more than 10V nominal and carefully check supply toler- components are preferred over decrete components for
ances under all conditions so that the voltages do not ex- minimum inductive effect
ceed the maximum Large values of feedback resistors can couple with parasitic
DIFFERENTIAL INPUT VOLTAGE capacitance and cause undersirable effects such as ringing
or oscillation in high speed amplifiers Feedback resistor
Differential input voltage is the difference in voltage be-
value around 1 kX is recommended
tween the non-inverting ( a ) input and the inverting (b) in-
put of the op amp The absolute maximum differential input COMPENSATION FOR INPUT CAPACITANCE
for the LM6317 is 10V across the inputs This limit also ap- The combination of an amplifier’s input capacitance with the
plies when there is no power supplied to the op amp This gain setting resistors adds a pole that can cause peaking or
may not be a problem in most conventional op amp designs oscillation To solve this problem a feedback capacitor with
however designers should avoid using the LM6317 as com- a value
parators or forcing the inputs to different voltages In some
CF l (RG c CIN) RF
designs diodes protection may be needed between the in-
puts as shown in Figure 1 can be used to cancel that pole The value of CIN can be
found in the DC Electrical Characteristics Table of the data-
sheet Figure 2 illustrates the compensation circuit
TL H 12542–20
FIGURE 1 Input Protection for LM6317 TL H 12542 – 21
FIGURE 2 Compensating for Input Capacitance
Layout Consideration
PRINTED CIRCUIT BOARDS AND HIGH SPEED
Power Supply Bypassing
OP AMPS Bypassing the power supply is necessary to maintain low
power supply impedance across frequency Both positive
There are many things to consider when designing PC
and negative power supplies should be bypassed individual-
boards for high speed op amps Without proper caution it is
ly by placing 0 01 mF creramic capacitors directly to power
very easy and frustrating to have excessive ringing oscilla-
supply pins and 2 2 mF tantalum capacitors close to the
tion and other degraded AC performance in high speed cir-
power supply pins
cuits As a rule the signal traces should be short and wide
to provide low inductance and low impedance paths Any
unused board space needs be grounded to reduce stray
signal pickup Critical components should also be grounded
at a common point to eliminate voltage drop Sockets add
capacitance to the board and can affect frequency perform-
ance It is better to solder the amplifier directly into the PC
board without using any socket
USING PROBES
Active (FET) probes are ideal for taking high frequency
measurements because they have wide bandwidth high in-
put impedance and low input capacitance However the
probe ground leads provide a long ground loop that will pro-
duce errors in measurement Instead the probes can be
grounded directly by removing the ground leads and probe
jackets and using scope probe jacks
TL H 12542 – 22
FIGURE 3 Power Supply Bypassing
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Application Notes (Continued) Other High Speed and Video
Amplifiers
Termination National Semiconductor has an extensive line of high speed
In high frequency applications reflections occur if signals amplifiers with a range of operating voltage from 3V single
are not properly terminated To minimize reflection coaxial supply to g 15V and a range of package types such as the
cable with matching characteristic impedance to the signal space saving SOT23-5 TinyPakTM (3 05mm c 3 00mm c
source should be used The other end of the cable should 1 43mm - about the size of a grain of rice) and a wide SO-8
be terminated with the same value terminator or resistor for better power dissipation
For the commonly used cables RG59 has 75X characteris-
This op amp line includes -
tics impedance and RG58 has 50X characteristics imped-
ance LM6171 100 MHz low distortion amplifier with greater than
3000V ms slew rate Voltage feedback design
draws only 2 5 mA Specified at g 15V and g 5V
Driving Capacitive Loads supplies
Amplifiers driving capacitive loads can oscillate or have ring-
LM7131 TinyPak (SOT23-5) video amplifier with 70 MHz
ing at the output To eliminate oscillation or reduce ringing
an isolation resistor can be placed as shown below in gain bandwidth Specified at 3V 5V and g 5V sup-
plies
Figure 4 The combination of the isolation resistor and the
load capacitor froms a pole to incease stability by adding LM7171 200 MHz voltage feedback amplifier with 100 mA
more phase margin to the overall system The desired per- output current and 4000V ms slew rate Supply
formance depends on the value of the isolation resistor the current of 6 5 mA Specified at g 15V and g 5V
bigger the isolation resistor the more damped the pulse supplies
response becomes A 50X isolation resistor is recommend- Information on these parts is available from your National
ed for initial evaluation Semiconductor representative
TL H 12542 – 23
FIGURE 4 Driving Capacitive Load
Physical Dimensions inches (millimeters) unless otherwise noted
8-Pin Small Outline
Order Number LM6317IM or LM6317IMX
NSC Package Number M08A
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LM6317 120 MHz Fast Settling Low Power Voltage Feedback Amplifier
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
8-Pin DIP
Order Number LM6317IN
NSC Package Number N08E
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL
SEMICONDUCTOR CORPORATION As used herein
1 Life support devices or systems are devices or 2 A critical component is any component of a life
systems which (a) are intended for surgical implant support device or system whose failure to perform can
into the body or (b) support or sustain life and whose be reasonably expected to cause the failure of the life
failure to perform when properly used in accordance support device or system or to affect its safety or
with instructions for use provided in the labeling can effectiveness
be reasonably expected to result in a significant injury
to the user
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National does not assume any responsibility for use of any circuitry described no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications